> 7. Ability to run a small chatroom for free which AFAIK Microsoft doesn't offer (its included with other Microsoft products that were paid for usually)

Looks like there's a free [0] version of teams that supports unlimited search, unlimited app integrations and meetings of up to 100 attendees. Compare to free [1] slack that has limitations of 10k searchable messages, 10 app integrations and only 1-1 meetings

[0]: https://www.microsoft.com/en-au/microsoft-365/microsoft-team... [1]: https://slack.com/intl/en-au/pricing